I still can't believe this is an issue that DJI haven't fixed, but I randomly (about 30% of my shots) end up with video files that have the audio out of sync. In some cases it's seconds ahead of the video, and there's blank space with no sound at the end. So far it hasn't been too bad it hasn't lost any important audio, but it's a pain to resync, and one of these days it'll cut out something I need.
I shoot at 1080p60, NTSC, MP4
RODE Video Micro microphone (I'm not sure if it has the sync problem while using the built-in mic, I haven't tested since that mic is unusable)
Recording to a SanDisk Extreme microSDXC UHS Video Speed Class 30 (V30) 90MB/s read, 60 MB/s write (30MB/s sustained)

I know I could record to a field recorder, but that defeats the purpose of having an all-in-one kit like the Osmo.

Please tell me I'm doing something wrong and this can be fixed without having to wait for DJI to try and fix it.

Megaman, sorry for the trouble caused, we would suggest to test the built-in mic to see if the problem persist.
This issue barely occurs since a long time ago, and the new firmware of Osmo will be released very soon, please update in time.